Uncontrolled railroad crossing warning signs include A. round black-on-yellow warning signs.

B. red flashing lights.

C. crossing gates.

D. none of the above

4. what is the reason for including the following code snippet in the header file animal.h? #ifndef animal_h #define animal_h class animal { public: animal(); animal(double new_area_hunt); void birth(); void hunt(double new_area_hunt); void death(); double get_area_hunt() const; private: double area_hunt; }; #endif